A method for predicting the subgrade uplift intensity along a high-speed railway track in red-bed areas in China

The operational safety of high-speed railways (HSRs) mainly relies on the flatness of their track surfaces. In recent years, continuous and stable subgrade uplift deformations in red-bed mudstone strata have occurred beneath several HSRs in southwest China, severely affecting the regular operation of HSRs. This study proposed a method for predicting the subgrade uplift intensity of the Chengdu-Chongqing passenger dedicated line (CCPDL) and determined the subgrade uplift mechanisms of the CCPDL through mudstone creep experiments, mineral composition analysis, and the statistical analysis of monitoring data on the uplift. Five parameters were selected as prediction indices, namely the excavation height of the subgrade center, dip angle, the characteristics of sandstone-mudstone interbeds, saturated uniaxial compressive strength, and mudstone expansibility. The weights of these five indices were determined using both subjective and objective weighting methods. The relationships between prediction indices and actual uplift intensities were analyzed using the ideal point method (IPM). Then, the optimal prediction model was proposed through precision and error analyses. Finally, the feasibility and applicability of the prediction model proposed in this study were verified through engineering case analyses. The prediction model proposed in this study can be used as a reference for similar engineering challenges in red-bed areas.